The addition of milk to tea in Europe was first mentioned in 1680 by the epistolist Madame de Sévigné.
Adding tea to milk is partially a matter of taste: but some teas are too delicate in flavour to be so modified.
There is some discussion as to whether the milk or the tea should be added first to the cup. In earlier periods, according to one version, cups were delicate - so the milk was poured first to prevent the porcelain from cracking. Adding the milk after the tea, however prevents the milk from being affected so much by the heat.
Cream or higher fat milks are often used instead of lower fat milk. Creme, a cream substitute, is used by lactose intolerant people, sometimes as a lower calorie option. Lemon juice or slices are also a popular additive for tea, but it is generally best to not add both dairy and citrus to the same cup of tea as the citrus will cause the milk to curdle. Sugar and honey are also popular tea "condiments".
See also Tea with alcohol and With milk.